1. Field of the Invention
This invention relates to an air bag and a folding method that will permit an air bag device to be desirably inflated when necessary. In particular, the invention concerns an air bag for side collision protection which is arranged between a passenger and a vehicle wall such as a door.
2. Description of the Prior Art
Heretofore, passenger air bags and driver side collision air bags (hereinafter referred to as "a side collision air bag", when applicable) have been formed by sewing two pieces of cloth material which are substantially rectangular. Hence, the air bag is substantially rectangular when inflated. The air bag is connected to the inflator of the air bag device, and folded down, and accommodated in a seat or similar structure.
The air bag is folded down according to a folding method so that it will be quickly inflated (cf. Japanese Patent Publication No. Hei. 5-139238).
In the folding method as shown in FIGS. 1 to 3, which is a form of telescoping procedure, the front end portion 3 of the air bag, which moves outwardly upon inflation in an emergency, is pushed inwardly towards the rear end portion 2 of the air bag; that is, it is inserted into the rear end portion 2. This operation is repeatedly carried out, so that the front end portion 3 of the air bag is folded down while being shrunk. Hence, it is difficult to mechanically fold the air bag, and it is necessary to fold down manually.
As described above, the front end portion 3 is pushed into the rear end portion 3, and this pushing operation must be carried out repeatedly. In addition, the front end portion 3 is equal both in outside diameter and in inside diameter to the rear end portion. Hence, the manual folding operation requires many man-hours and additional time to couple the folded air bag to the body of the air bag device. Accordingly, the resultant air bag device has high manufacturing costs.